Machinery for the hydraulic transmission of power.



H. D. WILLIAMS. MACHINERY FOR THE HYDRAULIC TRANSMISSION OF POWER.

. APPLICATION FILED APR. 4,1911. 1,047,600. Patented Dec. 17,1912.

j vemor.

fliforney UNITED STATES PATENT OFFICE.

HARVEY .fIOOL COMPANY, OF WATERB'URY, CONNECTICUT, ACORIOBA'IION.

MACHINERY FOR TIIE HYDRAULIC TRANSMISSION OF POWER.

' Application filed April 4,

circulation of a liquid. The pump is shaftdriven at a constant number of revolutions,

but the volumetric output of the pump can be varied at will by varying the stroke of the pump pistons. The same device which permits the-output of the pump to be var ed permits also of the reversal of the dlrectlon of circulation within the fluid connections betweengthe pump and the motor. Thus the motor which is of any ordinary type of hydraulic motor may. be readily reversed and the speed may be controlled with great? nicety by appropriate manipulations of the stroke varying device in the pump.

It is' characteristic of this type of variable speed gears that the working stresses in the machine may, under certain normal conproport onally ditions of working, increase as the speed of the motor diminishes. Thus as the speed of the motor approaches zero the stresses will become greater than the materials can withstand unless resort is had to some safety appliance. Heretofore this safety appliance has taken the form of a relief valve which permits some of the liquid to escapefrom the circulatory system whenever the pressure of the liquidexceeds-a certain maximum amount corresponding to the compression setting of the relief. valve spring. The escape of liquid from theci'rculatory system leaves voids therein which quickly attain. a volume comparableto the displacement of the pump pistons following which the chain of resistance between pump and motor is entirely broken and the pump continues its revolutions under practically.

noload.

This type of safety appliance has the meritof affording ample relief with a valve of diminutive size. Also the no-load con-- I Specification of Letters Patent.

' Patented Dec. 1'7, 1912.

1911. Serial No. 618,954.

dition which an excessive load quickly induces prevents the generation of a great quantity of heat within the working partsv of the machine. On the other hand the operation of this safety device is very noisy and it puts the machine temporarily out of service.

The object of my invent-ion is to provide a safety appliance which permits the circumachine out of service. safety appliance is particularly applicable and desirable when the quantity of the circulating liquid is great enough so that from the one disclosed in the patent above cause the positive-stop to the movement in either directlon of the plunger 10 is-a con- Inands on a safety device, while the heat d1fiiculty referred to above is mitigated by required to fill motor 6. 1

The major part of the by-pass from 12 to pass and is its most essential. part.

ody of the safety valve 153s providedwith cored passages which allow free communicaand the space 17. Other cored passagesiallow free communication between the pipe 13, the annular port 18 and thespace19.

lating liquid to by-pass the overloaded motor, thus affording relief without putting the Such a by-pass of the circulation and-the direction of'thej D. WILLIAMS, 0! NEWPORT, RHODE ISLAND, ASSIGNOR TO THE WATEEBUBY the heat generated within itduring anover- I load will not cause atooquick rise oftem- Referring to the accompanying drawing The pump 2 circulates a liquid (lubricating the control shaft 5'. The pipes 4 and 14 lead motor 6. The purpose of this particular shaft 7 through the medium of the arm 8,

referred to, is used here for illustration be dition which might well make;;,;frequent de the comparatively large volume of liquid 2" the opposed cylinders of the ioo 13 is cut away. in the drawing in order toi show to a larger scale the'details of. the: safety valve which is inserted in the bytion between thepipe 12,-the' annular port 16 fitting socket wrench 31.

The annular ports 16 and 18 are closable respectively by the check valves 20-and 21 both of which valves are held against their seats by the force of the spring 22. The

force of the spring is imparted to the valve 20 through the medium of the washer 23 which, by virtue of a spherical contact with the valve 20, insures the central application to the valve 20 of the force of the spring 22.

The exactly equal and opposite force of the.

Y 19 through a plurality of grooves 29 which last however are not permitted to interfere with a nice sliding fit of the valve 20 on the stem '26. By thus providing for the free escape of liquid from the inner edges of the annular ports 16 and 18 the lift required of the valves for a given dischar e opening is much less than it would be if t e escape were confined to the outer edges of those ports. The flanged collar 24 is prevented from turning on the stem 26 by a key in 24 on aging the keyway 30in 26.

The tension 0 the spring 22 is adjusted by turning the nut 25 by means of the loosely Since the space 19 is of necessity closed in by'the spring case 32 the socket wrench, in order to be turnable from the outside, is provided with a squareended spindle 33 which pierces the spring case 32 the two being locked .together on the outside by the nut34. It is thus possible to adjust the tension on the safety valve s ring while the machine is in operation and? with the higher pressure at either end of the by-pa'ss. The tapped hole which is shown stopped by plug 35 is for the connection of a pressure gage in case it is de sired to know ---the pressure at which the .safety valve will open.

In the operation of the machine the pump 2 normally induces a circulatign throughethe pipes 4 and one cylinder of the motor 6 and forcing an- 14 withdrawing liquid from equal volume of liquid into the opposed cylinder. Under these conditions there will be no circulation through the Toy-pass 12, 13."

.motor to the by-pass by the openin But in case 01- an unyielding resistance to the movement of the plunger 10 orin case of a great external force being applied to the same, causing an excessive pressure in either of the cylinders of the motor, the circulation automatically shifts from the safety valve in the latter. So soon' owever asthe cause of the excessive pressure has been removed the safety valve closes and the circulation shifts back againfrom the by pass to the motor.

I claim:

1: A hydraulic mechanism comprising a pump, a motor, fluid connections between the two whereby the pump can drive the motor in either direction, a by-pass paralleling the motor, a safety valve in'the bypass, the safety valve comprising two relief of the I I valves for relieving pressure at either end of the b -pass, one spring for loading both relief va ves whereby the load on each relief valve is the reaction from the load on the other valve, a coaxial arrangement of the spring and the relief valves, awasher interposed between thev spring and one of the relief valves, a spherical joint between the washer and the contacting valve, .means comprising a screw thread and a nut for adjusting the load on the spring, the said ad- 'justing means together with the spring and the valves inclosed within a fluid tight casing, a wrench piercin' the casing by a turning joint and adapte for turning the nut on the inside of the casing by a stem projecting outside thereof, substantially as describ 2. A safety valve comprising two check valves arranged in parallel between two pipe connections, each check valve closable by and against a pressure which tends to open the other valve, each valve held against its seat by the force of a spring the reaction of which is the load on the other valve, each valve contacting with its seat along an inner and an outer edge, the area of the port opening being confined to the annular area between the said edges, substantially as described.

In witness whereof I have hereunto set my hand in the 'presence of two subscribing witnesses.

Witnesses: MARTHA BURDIGK, a

GEORGE J. SoHonNEMaN.

. HARVEY n. WILLIAMS. 

